Why would a mushroom be named “fly agaric”? I couldn’t find a clear answer to this, but “fly” could refer to
its historical use as a fly killer, since it contains ibotenic acid. Or it could refer to the delirium it induces if
eaten. “Agaric” roughly translates to “mushroom”—it refers to a fungal fruiting body that has a cap that is
clearly differentiated from the stalk, with gills on the underside of the cap. In any case, amanitas are
attractive, common, and dangerous. Amanitas are the iconic toadstool, or poisonous mushroom.

Identification: Caps are bright red in western varieties, orange or yellow
in northern and eastern locales; with white, warty spots. They reach 1¾-12" (5-30 cm) in diameter, and can reach 12" (30 cm) in height. There are many varieties of amanitas—for a detailed key, see Michael Kuo’s
at mushroomexpert.com.

Edibility: Poisonous This species is not as poisonous
as several of its relatives, and
fatalities from eating them are rare, but they nevertheless cause a wide range of unpredictable symptoms.
From Wikipedia:

That’s if the effects are mild. Seizures, coma, and possibly death can occur with stronger doses. The effects of a given
dose vary enormously from person to person. There is no antidote. Despite the risks, many earlier peoples
have consumed it for its psychoactive effects, a practice that continues to a limited extent even today.

Amanita muscaria lacks significant amounts of amatoxins and phallotoxins, which make some
of the other amanitas so deadly. But they contain a chemical cocktail I wouldn’t mess with:

Roughly 75 people in North America are poisoned each year by mushrooms, often from eating a poisonous species that resembles an edible species. Though deaths are rare, there is no cure short of a liver transplant for severe poisoning. Don’t eat any mushroom unless you are absolutely certain of its identity! Please don’t trust the identifications on this site. We aren’t mushroom experts and we haven’t focused on safely identifying edible species.

1From The North American Guide to Common Poisonous Plants and Mushrooms; see reference above